Archive::Tar versions before 3.08 for Perl extract hardlinks to attacker controlled paths outside the extraction directory.

_make_special_file() passes the tar header's linkname to link() without validating it against absolute paths or .. segments, creating a hardlink that shares the victim file's inode.

A subsequent write through the extracted name modifies the victim file, and the post-extraction chmod, chown, and utime block in _extract_file() (guarded only against symlinks via -l) applies the tar header's mode, owner, and timestamps to the shared inode during extraction alone.